Figure 2: The process involving a robot generating hundreds of experiments, tools to analyze the results and a computer to turn it into a pretty picture showing the results is a formulator’s dream.

Not so—many observations, too, can be
automated. A spectrophotometer can
measure concentrations, and a crossed
polarizer reveals liquid crystal structures.
Adhesion (tackiness) can be measured with
a ;exible lens test.

Robert Lochhead1, 2, 3 is a pioneer in
applying combinatorial chemistry to personal
care applications. He has used the interaction
of a cationic polymer with an anionic
surfactant as an example in his publications.
And this combination is critical for the
modern conditioning shampoo.

;e basic science was unraveled by
E. Desmond Goddard4 in seminal papers
published in the early 1990s. It is complicated
unless one is a polymer chemist, but the
basic idea is that the interaction of a polymer
with a surfactant changes with conditions,
such as the amount of solvent present. It is
possible for the polymer and surfactant to
live happily together for a while but separate
upon dilution.

;e separation of phases allows the
polymer to deposit on the hair, rather than
wash o; with the surfactant. Since the
interactions are complex, a robot generating
hundreds of experiments, tools to analyze the

70 Chemical Reaction

results and a computer to turn it into a pretty
picture showing the results is a formulator’s
dream. ;e process, highly simpli;ed, is
shown in Figure 2.

;e triangular phase diagram shows
regions where coacervates are absent and
others with a maximum concentration of
phase-separated coacervate. ;e diagrams
are di;erent for every polymer. Surfactant
composition and electrolyte concentration
are some other key variables.

It is formidable technology, yet it is, in
essence, but an extension of a salt curve.
Data is gathered, plotted and informed
decisions made. It takes the rather haphazard
way much cosmetic formulation is done
and places it in a formal platform, allowing
vastly increased data entry and information
processing.

At the beginning of a study, informedhumans are required to establish thetest criteria. When the robots, analyzingdevices and computers are done, there isstill room for human intervention. ;eresults must be con;rmed in a lab underthe usual formulation conditions. ;e datausually involves speci;c components ofthe formulation, not the complete product,so conventional methods are employedto achieve the ;nal formulation. So at theend, people are still needed, but they havewonderful new tools that allow the creationof technically advanced products. n GCI

STEVE HERMAN is president of Diffusion LLC, a consulting company specializing in regulatory issues, intellectual property, and technology development and transfer. He is a principal in PJS Partners, offering formulation, marketing and technology solutions for the
personal care and fragrance industry. He is an adjunct professor
in the Fairleigh Dickinson University Masters in Cosmetic Science
program and is a Fellow in the Society of Cosmetic Chemists.